Interpretive Summary: Saw palmetto and pygeum are natural products commonly used in dietary supplements for the treatment of enlarged prostate glands. These plant materials are rich in fatty acids, and the fatty acid compositions of both plants are similar. The goal of this study was to develop a gas chromatography-mass spectroscopy (GC/EI-MS-SIM) method that could be used to chemically distinguish the two species in dietary supplements. Two authenticated plant samples, two commercial plant extracts, one NIST SRM extract and twenty-one commercial dietary supplements purported to contain either saw palmetto, pygeum or both were investigated. Fatty acid methyl esters (FAMEs) were analyzed by GC/MS in a selected ion monitoring mode. The major fatty acid components that were common to both saw palmetto and pygeum determined in this study were oleic acid, linoleic acid and palmitic acid. The major component characteristic of pygeum was stearic acid. Lauric and myristic acids were observed predominantly in saw palmetto samples. The use of selected ion monitor mode for the GC/MS analysis allowed accurate quantitation of all detected FAMEs even those that were not chromatographically resolved. The proposed GC/MS method is useful for chemical fingerprint analysis and quality control of dietary supplements claiming to contain pygeum and/or saw palmetto. Principal component analysis was used for interpretation of the analytical results. A distinct cluster was observed for samples containing pygeum alone. A separate cluster was observed for samples containing saw palmetto alone or mixed with pygeum.

Technical Abstract:
Saw palmetto and pygeum are natural products commonly used in dietary supplements for the treatment of enlarged prostate glands. These plant materials are rich in fatty acids, and the fatty acid compositions of both plants are similar. The goal of this study was to develop a gas chromatography-mass spectroscopy (GC/EI-MS-SIM) method that could be used to chemically distinguish the two species in dietary supplements. Two authenticated plant samples, two commercial plant extracts, one NIST SRM extract and twenty-one commercial dietary supplements purported to contain either saw palmetto, pygeum or both were investigated. Fatty acid methyl esters (FAMEs) were analyzed by GC/MS in a selected ion monitoring mode. The major fatty acid components that were common to both saw palmetto and pygeum determined in this study were oleic acid, linoleic acid and palmitic acid. The major component characteristic of pygeum was stearic acid. Lauric and myristic acids were observed predominantly in saw palmetto samples. The use of selected ion monitor mode for the GC/MS analysis allowed accurate quantitation of all detected FAMEs even those that were not chromatographically resolved. The proposed GC/MS method is useful for chemical fingerprint analysis and quality control of dietary supplements claiming to contain pygeum and/or saw palmetto. Principal component analysis was used for interpretation of the analytical results. A distinct cluster was observed for samples containing pygeum alone. A separate cluster was observed for samples containing saw palmetto alone or mixed with pygeum.